1. Field of the Invention
The present invention relates to a motor, and more particularly, to a motor capable of having a control function for low-speed rotation by including an encoder on the bottom surface of a ring member mounted on a rotor case, and an encoder sensor located corresponding to the encoder.
2. Description of the Related Art
In general, a spindle motor installed inside an optical disc drive rotates a disc so that an optical pickup mechanism can read data written to the disc.
Recently, an optical disc drive equipped with a LightScribe function has been increasingly released onto the market. Here, the LightScribe function allows users to print letters (characters) or images freely on the upper side of a disc such as a DVD, a CD or the like.
According to the related art, only LightScribe discs that support the LightScribe function by having a printed encoder generating an FG pulse for low-speed control are able to be used in order to implement the LightScribe function. Here, typical discs for recording cannot be used in realizing the LightScribe function.
That is, in order to use the LightScribe function, a spindle motor needs to rotate at a low speed of 40 rpm to 300 rpm or less. Thus, an encoder generating a separate FG pulse is printed on the side of a disc, since the FG pulse of the spindle motor itself, cannot be used for the LightScribe function.
However, the use of such LightScribe discs has limitations in that the discs are costly and are not easy to buy.
In addition, since LightScribe printing is performed on the opposite side to the read/write-side of a disc, the LightScribe disc is repetitively taken out from and put back into a chucking device. This may damage an encoder printed on the LightScribe disc.
Further, the encoder, when printed on a disc in a non-uniform manner, fails to perform precise low-speed control and impairs printing quality.